PREVALENCE AND EXTENT OF GLACIATED BASINS. ■J!> , .> 



its eastern border of Azoic and its western of Paleozoic rocks, it bears con- 

 siderable resemblance to the vanished Lake Agassiz. If the Hudson's bay 

 region were raised bodily and evenly only about 400 feet, all its waters 

 would drain away, leaving an almost perfectly level plain unequalled for 

 extent in North America, and with the largest river in the world flowing 

 out at its northeastern angle ; but if it were canted so as to give a grade as 

 low as a single foot in the mile from north to south, it would separate from 

 Hudson's strait and become a gigantic fresh-water lake, discharging by the 

 continuous valley which follows the Albany and Kenogami rivers, Long lake, 

 and the Black river to Lake Superior, passing near the site of the cluster of 

 wonderful pot-holes described by Mr. McKellar. As the land was probably 

 much more elevated than this in the north during the glacial period and the 

 basin of Hudson's bay filled with fresh-water ice, it is not impossible that 

 towards the close of the period this ice became liquefied and that for a time 

 we really had a fresh-water lake larger than the present Hudson's bay. If 

 this were so, Lake Agassiz, large as it was, would be completely dwarfed 

 and Lake Superior, now the greatest lake in the world, would become a 

 mere pond in comparison. 



The enormous glaciated Archeau region of Canada is preeminently the 

 land of lakes, and has no parallel in the world. Leaving out the great 

 border lakes already referred to, those within the limits vary in size from 

 170 miles in length, like Reindeer lake, down to a few hundred yards. 

 Among lakes from 40 or 50 to 100 miles in length may be named Aylmer, 

 Cree, North-lined, Wollaston or Hatchet, Reindeer, La Plonge, La Rouge, 

 Montreal, South Indian, Burntwood, Simon, Split, Sipi-wesk, God's, Island, 

 Trout, Lonely, St. Joseph or Osnaburgh, Rainy, Long, Temagami, Abittibi, 

 Teiniscaming, Keepawa, Grand, Nipissing, Mistassini, Michigama, and many 

 others whose names are entirely unknown to geography. Lakes of smaller 

 size count literally by the ten thousand. In some whole districts it is esti- 

 mated that nearly one-half and certainly one-fourth of the entire area is 

 occupied by these sheets of water. They are nearly all rock-basins, com- 

 paratively few of them being held in by moraines or loose material in any 

 form. They often run in chains or systems, in different courses, thus forming 

 canoe-routes by which one may travel in almost any desired direction. The 

 lakes constituting these chains often discharge into one another by a suc- 

 cession of short links of river. The upper Ottawa, the English river, which 

 discharges Lonely lake into the Winnipeg, and the Churchill from its source 

 to where it enters upon the Paleozoic rocks, are among the examples of these 

 chains of alternating lake and river. 



Reaction of Rock Structure on Glacial Erosion.— The arrangement of the 

 lakes in the patterns above referred to is due, originally, to glaciatiou in 

 connection with preexisting geological causes. Among these may be men- 



